Physics Paper 1: Energy Flashcards
What is kinetic energy?
The energy stored in moving objects
How do you calculate kinetic energy?
Kinetic energy = 0.5 x mass x speed
What is elastic potential energy?
When we put force on an object, this may cause it to change shape
What is the equation for elastic potential energy?
Elastic potential energy= 0.5 x spring constant x extension
What is gravitational potential energy?
Energy stored in an object due to its position above the earths surface- this is due to the force of gravity acting on the object
What is the equation to calculate gravitational potential energy?
Gravitational potential energy= mass (kg) x gravitational field strength (N/kg) x height (m)
What is specific heat capacity?
The amount of energy required to raise the temperature of 1kg of a substance by 1 degrees
What is the law of conservation of energy?
Energy can be transferred usefully, stored or dissipated but it cannot be created or destroyed
What is a system?
An object or a group of objects
What is a closed system?
No energy can enter or leave
What is the problem with this model of energy transfer in the pendulum?
We have not considered friction, friction caused energy to be transferred to thermal energy, the fixed point of the pendulum gets warmer
Why are these stores of thermal energy in the pendulum less useful?
The energy has been dissipated (wasted), this will cause the pendulum to gradually stop swing with less energy and eventually stop
How can we reduce unwanted energy transfers in the pendulum?
by reducing friction
.can use a lubricant such as oil on the fixed point
.removing air particles from around the pendulum
How is energy transferred through a bungee jumper?
.At the start of the jump all of the energy in the system is the store of gravitational potential energy
.As the jumper falls, energy is transferred from the gravitational potential energy store to the kinetic energy store
.When the bungee rope just starts to tighten, the kinetic energy store is now at it’s maximum
.When the rope is fully extended, the kinetic energy store is zero. The jumper is not moving. All of the energy has been transferred to the elastic potential energy store
.The bungee rope now recoils and energy is now transferred from the elastic potential energy store back to kinetic energy store
.during the ascent energy transfers from the kinetic energy store back to the gravitational potential energy store
.and finally at the top of the ascent, all of the energy is now in the gravitational potential energy store
Why does the bungee jumper never return back to its original position?
Because energy is dissipated as thermal energy such as by friction with air particles and stretching effects in the bungee rope which is not fully elastic
